1. Field of the Invention
The present invention relates to a method of manufacturing a disk drive device and a disk drive device manufactured by the method, and in particular, to a method of manufacturing a disk drive device to which a reduced amount of particles attaches and a disk drive device manufactured by the method.
2. Description of the Related Art
Recently, disk drive devices such as an HDD (Hard Disk Drive) have been required to be small in size and increased in capacity. For example, a disk drive device magnetically storing data rotates a recording disk having recording tracks at a high speed, so that a read/write operation of data is executed while a magnetic head of the device is floating above the recording tracks so as to maintain a slight gap between them. In order for such a disk drive device to be small in size and increased in capacity, a width of the recording track is required to be narrow. As the width of the recording track becomes narrower, the gap between the magnetic head and the recording disk is required to be further smaller. For example, the gap between the magnetic head and the recording disk is required to be as extremely small as 10 nm or less.
In order for the disk drive device to be small in size, a magnetoresistive effect element (hereinafter, referred to as an MR element) is used for the magnetic head. On the other hand, the use of the MR element in such a small gap causes a fear that a thermal asperity failure (hereinafter, referred to as a TA failure) or a head crash failure may occur in the magnetic head. Specifically, the TA failure means that: minor foreign substances on the surface of the recording disk are in contact with the MR element while the magnetic head is floating to trace the recording tracks, and therefore heat is momentarily caused in the MR element due to kinetic energy of the foreign substances; and a resistance value of the MR element is momentarily varied due to momentary heating or cooling of the MR element, resulting in superimposition of the varied resistance value on a reproduced signal as a noise, and interference with correct reading of the reproduced signal.
As a result of intensive study by the present inventor, it has been known that the TA failure occurs due to the fact that foreign substances having sizes of 0.1 μm to approximately several μm (hereinafter, referred to as “particles”) that attach to a disk drive device, then attach to the surface of the recording disk due to a vibration or an air flow. Herein, Japanese patent Application Publication No. Hei 7-124529 discloses a cleaning apparatus that cleans various parts such as a base.
Even when the base is cleaned, however, particles possibly attach thereto in a step of fixing a bearing unit and a hub to the base. For example, in the first case, particles attaching to assembly equipment, tools or tips of workers' hands possibly transfer to the disk drive device. In the second case, when an adhesive is used for fixing the bearing unit and the hub to the base, a component included in the adhesive may fly in all directions and attach to the surfaces of the bearing unit and the hub, causing particles attaching thereto. In the third case, when soldering and welding, for example, are to be used for connection of electric wirings in the drive unit, etc., particles possibly fly in all directions and attach to the surfaces of the base, the drive unit and the hub while soldering and welding are being performed, causing particles attaching thereto.
As stated above, the particles attaching thereto while fixing parts, cannot be removed by a conventional method of manufacturing a disk drive device, and hence a cleanness level inside a general disk drive device is low. Remaining of many particles causes a high incidence of the TA failure when the gap in which the magnetic head floats becomes small, resulting in interference with miniaturization and increased capacity of the disk drive device.